Cancer is a worldwide problem. Finding novel compositions and methods for treating cancer is of interest. The treatment of cancer falls into three general categories: chemotherapy, radiation therapy and surgery. Often, therapies are combined since a combination of therapies increases the probability the cancer will be eradicated as compared to treatment strategies utilizing a single therapy. Typically, the surgical excision of large tumor masses is followed by chemotherapy and/or radiation therapy.
Chemotherapeutic agents can work in a number of ways. For example, chemotherapeutics can work by interfering with cell cycle progression or by generating DNA strand breaks. If the cancer cell is not able to overcome the cell cycle blockage or cell injury caused by the therapeutic compound, the cell will often die via apoptotic mechanisms. The use of a single chemotherapeutic agent in the treatment of cancer, with or without surgery or radiation, has several disadvantages. Commonly, cancer cells develop resistance to the chemotherapeutic agent. Such resistance results either in the requirement for higher dosages of the drug and/or the renewed spread of the cancer. Chemotherapeutic agents can be toxic to the patient. Therefore, there is a practical upper limit to the amount that a patient can receive. However, if a second agent can be developed to inhibit the pathway causing resistance, cancer cells may become susceptible to the effects of the chemotherapeutic agent.
The design of a drug to overcome resistance to the chemotherapeutic treatment of cancer should be approached with the goals of 1) finding a combination that reverses resistance and not merely improves the activity of the chemotherapeutic with respect to activity on the tumor, and 2) finding a second drug that does not potentiate the toxic effects of the first chemotherapeutic agent. These conditions require a great deal of empirical testing of agents known to have anticancer properties with agents that either may have anticancer properties, or that may augment the first agent in other ways. Unfortunately, such approaches have thus far proven largely unsuccessful for combinations of many anticancer agents. Therefore, there exist insufficient therapies that reverse resistance to chemotherapy for the treatment of cancer.